Pale-headed brush-finch (Atlapetes pallidiceps)

Kingdom

Animalia

Phylum

Chordata

Class

Aves

Order

Passeriformes

Family

Emberizidae

Genus

Atlapetes (1)

Size

Length: 16 cm (2)

The pale-headed brush-finch is classified as Endangered (EN) on the IUCN Red List (1).

Until its incredible rediscovery in 1998, the pale-headed brush-finch (Atlapetes pallidiceps) was thought to be extinct, having not been seen since 1969 (3). As its common name implies, this small bird has a pale-coloured head, which is creamy white with ill-defined buff stripes on the sides of the crown and behind the eye. Upperparts are a light brownish-grey, while underparts are usually whitish (2). A small, distinctive white patch also exists on the side of the relatively dark wings.

This species has an extremely restricted range, being endemic to just a small semi-arid valley of the Río Jubones drainage in Azuay and Loja, south-western Ecuador (2) (4). Most pairs occur in the Yunguilla Reserve (5). The total population of the Endangered pale-headed brush-finch was estimated to be just 50 pairs in 2005 (3), but numbers are increasing (2).

The pale-headed brush-finch occurs in arid areas at 1,650 to 1,800 metre above sea level, favouring semi-open habitats with low scrub. Fairly dense scrub is tolerated, but forests and completely open areas are avoided. Nests are built within dense thickets of small bushes or bamboo, often covered with vines (2) (5) (6).

The pale-headed brush-finch is usually seen in pairs, which have been recorded breeding from anywhere between mid-January and late June, although no pairs have been observed successfully producing more than one clutch within a season. The chicks hatch after an incubation period of 14 to 15 days, and then proceed to be fed by their parents every 5 to 25 minutes, depending upon their age. Even after fledging, the young continue to depend upon their parents for food for at least a further four weeks (5). The pale-headed brush-finch is frequently a victim of nest parasitism by the shiny cowbird (Molothrus bonariensis), in which the latter species removes the existing eggs from the nest and replaces it with its own virtually identical eggs, to be incubated and raised by the pale-headed brush-finch (4).

This bird usually forages in pairs, finding most of its food around two metres above the ground (2). The diet consists of arthropods, fruit and a few seeds, with the arthropods almost invariably gleaned from twigs and small branches, while seeds are taken from the ground (7).

Habitat loss from human landscape modification seems to be the primary reason for the bird’s limited distribution, and remains a major concern for the species’ long term survival (4) (5). In the arid valleys of the Río Jubones drainage, areas where water is available have been widely cultivated, and large numbers of cattle and goats have stripped the area of vegetation (2) (3). Local use of fires to clear vegetation also potentially threatens suitable habitat, particularly if these fires get out of control (2). Another major threat is brood parasitism from the shiny cowbird, which has expanded its range considerably in recent decades and is now the most widespread brood parasite of South America and abundant in the Río Jubones drainage (4). Brood parasitism has significantly impacted the breeding success of the pale-headed brush-finch, with a shocking 61 percent of pairs breeding in Yunguilla Reserve parasitized in 2002 (5).

After the rediscovery of this rare bird in 1998, the small 27 hectares patch of suitable habitat in which it was found was purchased by Fundacion Jocotoco to form the Yunguilla Reserve, which has since been progressively expanded to cover most of the known population (3). This Reserve has been securely fenced off to prevent grazing pressure, with a local landowner hired as a part time guardian. In 2002, a habitat management scheme was implemented to halt vegetation growth, and convert unsuitable to suitable habitat by selectively thinning dense thickets (2). In order to assess the success of the habitat management scheme implemented in 2002, a habitat occupancy monitoring scheme was set up with Fundacion Jocotoco in 2004 (2) (5). In 2003, a hunter was employed to remove shiny cowbirds from the reserve during the pale-headed brush-finch’s breeding season, with a resultant 69 cowbirds shot (5). Cowbird removal strongly increased reproductive success that year, with 16 chicks fledging in Yunguilla Reserve compared to just five the previous year (2). Further cowbird removal has been conducted and in 2005 the parasitism rate was down to two percent (3). Fundacion Jocotoco has also made repeated visits to local agencies, land owners and schools in order to raise local awareness of the plight of this species (5). These intensive conservation measures have helped save the species from immediate extinction, having significantly increased the population from just 10 to 12 pairs in 1999 to over 50 pairs in 2006, and approximate 230 mature individuals in 2011 (2) (3) (5). However, further population growth is thought to be strongly constrained by a lack of suitable habitat to accommodate it (2) (5). Thus, although great progress has been made since the pale-headed brush-finch’s rediscovery, much remains to be done to overcome the immediate threats to its long-term survival (5).